Open Source Software for Java
dotCMS
A hybrid content management system that includes classic CMS and Headless CMS features. With dotCMS content managers can create content that fuels the brand experience. The API-first approach provided by the headless part of dotCMS allows developers to build extremely fast front-ends with popular third-party front-end framework and deliver content optimally. The content management system allows content creators to build engaging and memorable content that can be reused across sites.
OpenCMS
OpenCMS is based on Java and XML technology that allows you to build highly customizable and interactive websites and portals. The open-source content management system includes a WYSIWYG editor and fully-featured Template Engine which is fully compliant with W3C standards.
Play Framework
A framework designed to make it easy to build web applications with Java & Scala. The Play Framework is is based on a lightweight, stateless, web-friendly architecture that follows a model-view-controller (MVC) pattern. While providing predictable and minimal resource consumption (CPU, memory, threads) suitable for highly-scalable applications. Play is written in Scala and can be used for all programming languages that can be compiled into JVM bytecode.
QuestDB
QuestDB is a relational column-oriented time series database designed for real-time analytics on time series and event data. It uses the SQL language and include extensions for time series data. QuestDB is released as free and open source software and distributed as a single binary including a trimmed version of the JVM (Java Virtual Machine) weighing in at only 24.5 MB.
JDownloader
JDownloader is a free, open-source download management tool with a huge community of developers that makes downloading as easy and fast as it should be. Users can start, stop or pause downloads, set bandwith limitations, auto-extract archives and much more.
Grails
Grails is powerful Groovy-based web application framework for the JVM built on top of Spring Boot.
BuddyCloud
Buddycloud is an open source project that helps developers add chat, video and social features to their app without being locked into a proprietary solution. With BuddyCloud it's easy to build communities that facilitates rich communication. The open-source toolset is written in Java and is designed to scale well and save you your team time, when building an online community.
Apache NiFi
With Apache NiFi you can automate the flow of data between software systems. Apache NiFi supports powerful and scalable directed graphs of data routing, transformation, and system mediation logic. Apache NiFi is highly configurable and provides an intuetive web-based user inferface that can be used to control and monitor your data flow. The software is developed by the Apache Foundation and released free and open-source under the Apache License 2.0.
I2P
The Invisible Internet Project or I2P for short is a fully encrypted private network layer that has been developed with privacy and security by design in order to provide protection for your activity, location and your identity. I2P ships with a router that connects you to the network and applications for sharing, communicating and building a fully encrypted private network layer.